Fire detection systems have been recognized as being useful and valuable in residential and commercial buildings in providing an early alarm in the event of a developing fire. From the point of view of responding to a fire condition and potentially evacuating some or all of the associated building, the earliest possible detection of the fire condition is preferred. One such system is illustrated in Tice et al., U.S. Pat. No. 4,916,432 assigned to the assignee of the present application and incorporated herein by reference.
Counterbalancing the need for early detection, is a need to minimize or eliminate, if possible, false or nuisance alarms. Such alarms occur as a result of electrical or other types of environmental noise present in buildings wherein the alarm systems are installed.
Additionally, it is known that different types of smoke detectors respond, in part, based on the type of smoke. For example, ionization-type detectors have a faster response to smoke from flaming fires than do photoelectric-type detectors. On the other hand, photoelectric-type smoke detectors have a faster response to smoke from smoldering fires.
Another parameter that can affect the number of nuisance alarms is detector sensitivity. A detector with a high sensitivity is more likely to produce nuisance alarms than one set to a low sensitivity. On the other hand, a detector with high sensitivity setting has the advantage of producing an alarm condition sooner than a detector with a lower sensitivity setting in the presence of an actual fire.
Thus, there continues to be a need for multiple sensor detection systems which take into account the characteristics of different types of potential or actual fires so as to minimize nuisance alarms yet provide a rapid response to developing fire conditions. Preferably, such systems could be manufactured and installed at a cost comparable to known systems.